1. Field of the Invention
The present invention relates to resolving the signal frequency output of a flow meter. More particularly, the invention relates to structure for adding enough signals between consecutive flow meter signals to provide a whole number of signals to resolve the smallest unit of a register.
2. Description of the Prior Art
All fluid meters have outputs of a certain number of signals for each unit of fluid passing through the meter. If the meter is a turbine meter, each blade carried past the electrical pick-up generates an electrical pulse which will actuate a register.
The design engineer has a choice of meter sizes and the number of meter blades rotated by the fluid passed through the meter. Also he has available registers with readouts in certain units of fluid. With these choices, the engineer puts together a system in which he attempts to match flow pulses with register units to provide satisfactory accuracy in the readout. However, there may not be a match between the number of pulses per quantitative unit of fluid passed through the meter and the units of the register.
A simple example will establish the problem. A turbine meter of one inch diameter may be available with a 10-bladed rotor. This meter size and number of blades will produce 938 pulses per gallon of fluid through the meter. The register reads down to 1/10 of a gallon. Obviously 93.8 pulses are produced for 1/10 of a gallon. Since only whole numbers may be set in as a dividing factor, 94 is as close as the system can get to 93.8 pulses so the register of the system reads down to the 1/10 gallon with an approximate error of 0.2 percent.
If the meter pulses could be increased five times, this error could be eliminated. 469 pulses, a whole number, would then register as 1/10 gallon. Each 1/10 gallon unit on the register would equal each 469 pulses from the pick-up of the turbine meter, and no error could be possible from this portion of the metering system.
The basic problem of the art is simple, multiply the pulse output of the turbine meter until a whole number of pulses equals the smallest registered quantity of fluid metered. The problem of the art flowing from the basic one is that of multiplying the pulse output with accuracy and a minimum of structure. There are available clock oscillators whose train of output voltage pulses can be controlled by the output pulses of a turbine meter. It is known to control the output train of the clock oscillator through a gate controlled by each pulse output of the turbine meter. However, this circuit is somewhat complicated and it is difficult to keep from chopping off a part of the pulses of the train at the start and end of the segment gated.
Simplification is always desirable of any electrical circuit. Also, it is fairly evident that there is a probability that chopping out segments of a pulse train output of a clock will not consistently fix the number of pulses for each segment. The gate will be cutting in the train while a pulse is only partially formed and slicing off part of a pulse at the end of the segment. The inaccuracy introduced into the prior art system is difficult to pin down. Still, reason tells us that this is one danger of error which should be eliminated.